Making an embedded database autocommit=flase

Here is what I am trying to do.

I have a OOBase native database that stores BLOB and CLOB fields. I have 
the BLOB field in one table with this field and a foriegn key columnonly 
, and the CLOB in a seperate table with just this and a foreign key 
column. Each of these LOB tables have a 1 to 1 relationship from a third 
table.

Naturally then, I would like to treat my edits to the database as 
transactions involving all three of these tables. This requires that 
autocommit=false. I can open the SQL window and enter SET AUTOCOMMIT 
FALSE, and this works fine. But I cannot figure out how to make this 
permanent, if that is even what I would like.

I would have thought that I could control this on a connection by 
connection bases, however whenever I try to set a connection that is 
opened in Basic with CONNECTION.setAutoCommit(False) I receive the error 
-  This call is not allowed when sharing connections.

First question I open the connections with a fairly standard peice of code
conn =  
CreateUnoService("com.sun.star.sdb.DatabaseContext").getByname("imgCatelogue").getConnection("", 
"" )
Is there something I should be doing different with the getconnection 
call, so that I can change THIS connection to autocommit=false.

Second question - Is there someway to make this database autocommit by 
default.

Thanks

Andrew